On the Zend Developer Zone today they've announced this month's Zend Framework Bug Hunt starting tomorrow (the 25th) and running through Saturday (the 27th):

For those who haven't put the recurring event in their calendar, the Zend Framework Monthly Bug-hunt is here again! This Thursday, Friday and Saturday (the 25th, 26th and 27th of August), we'll be hosting our monthly bug hunt. For those of you unfamiliar with the event, each month, we organize the community to help reduce the number of open issues reported against the framework

Ralph reminds everyone of the change in tracking methods in their Jira setup and how to find some issues to tackle when you start your debugging. You can also just visit this page to get the full list of unresolved issues. Additional instructions are included in the post on "getting started" resources, how your fixes help the framework and a guide you can follow to get the ball rolling.